Patent GB-281356-A (GB)
Title: Improvements in or relating to refrigerating systems
IPC: F25B43/04
Filed: 1926-07-20
Abstract: 281,356. Carrier, W. H., and Carrier Engineering Corporation. July 20, 1926. Refrigerating, vacuum systems for. -In systems of the kind described in Specifications 220,299, 230,936, and 263,052. wherein means are provided for cooling the mixture of dense refrigerant vapour and air withdrawn from the condenser so as to condense the refrigerant vapour and return it to the cycle and to discharge the air, regulating means are provided whereby a moderate flow of the air-vapour mixture through the cooler is obtained. with a small difference in pressure between the inlet and outlet sides of the cooler. Preferably the air-vapour mixture is first passed through a preliminary cooler wherein its heat is utilized to vaporize some of the liquefied refrigerant taken from the evaporator, so as to effect a rectification of the refrigerant. The air-vapour mixture flows from the coolers into a vacuum tank of considerable capacity, which is exhausted by a vacuum pump operating as occasion requires. The refrigerating plant comprises an evaporator A, through which the liquefied refrigerant falls in films over pipes conveying a medium to be cooled, an exhauster B, preferably of the centrifugal type, a surface condenser C, preliminary and main coolers 13, 14 for the air-vapour mixture, regulating devices 20, 22, a vacuum tank 10, vacuum pump 11, and other coolers 59, 40 and air and water separating devices 56, 65. The air-vapour mixture is preferably withdrawn from an ascending passage 12 in the condenser C, and flows through a pipe 15 to a coil 16 in the preliminary cooler 13. It then flows through a restriction or pressure-reducing device 25 to a coil 18 in the main cooler 14, and thence through the regulators 20, 22 and pipe 23 to the vacuum tank 10. Cold liquefied refrigerant collected in an open-topped stand pipe 41 in the evaporator A is led to the chamber 40 of the final cooler 55, then to the chamber of the main cooler 14 by way of a passage 43, and lastly by a pipe 45 fitted with a check valve 46 to the chamber of the preliminary cooler. The liquid refrigerant in the chamber of the preliminary cooler is vaporized by the heat of the air-vapour mixture in the coil 16 and is thus purified, the vapour being led through a passage 47 fitted with a manual valve 49. This vapour together with any vapour from the chambers 14, 40 is returned through a passage 48 to the evaporator. Oil and other impurities drain into a sump 50 having a drain cock 52. The liquid in the sump may be positively heated by means 51, just before the drain cock is opened, to vaporize and return to the evaporator any refrigerant liquid in the sump. A valved bye-pass pipe 68 is provided between the pipe 15 and the pipe 23 leading to the vacuum tank. whereby at starting the system may be exhausted without passing the vapours from the condenser through the coolers 13, 14. The airvapour mixture drawn from the vacuum tank occasionally by the pump 11 is delivered through an air-cooled coil 59 to the coil 55 in the final cooler 40, containing the coldest liquid refrigerant, and finally enters a tank 56. Air escapes from this tank through a valved vent-pipe 57, and condensate is passed through an automatic or manual valve 63 and pipe 64 to a tank 65. This tank receives condensate from the other coils 16, 18 through pipes 62, 63, and is provided with weir-like baffles to separate water, which is drained through a valved pipe 66. The condensed refrigerant is returned to the receiver 1 of the main condenser or to some other part of the liquid line. The regulating device comprises a diaphragm! 27, Fig. 2, dividing a casing 26 into a chamber 28 connected by a passage 30 with the inlet side of the main air-vapour cooler, and a chamber 29 connected by a passage 19 with the outlet side of the cooler. The valve 31 is pressed towards the open position by an adjustable spring 32, and the action is such that when the cooled air-vapour mixture contains little non- condensible gas, the consequent reduction of pressure in the chamber 29 of the device is insufficient to maintain the valve open against the superior pressure in the chamber 28. The regulating device 22 is of similar construction, but the spring corresponding with the spring 32, Fig. 2, is opposed by a stronger spring, and the chamber below the diaphragm is open to the vapour space of the rectifier chamber around the preliminary cooling-coil 16. The valve of this device closes when the vapour pressure increases in the chamber 13, due to rectification.